1. Field of the Invention:
The present invention relates to a gas-generating composition for the gas generator to supply a gas to the air bag, which is a safety fgeature that protects the driver and passengers in a car accident.
2. Description of the Prior Art:
There are several kinds of conventional gas-generating compositions composed mainly of an azide of alkali metal or alkaline earth metal and an oxidizer.
For example, there is described in U.S. Pat. No. 2,981,616 a gas-generating composition composed of an azide represented by M(N.sub.3).sub.x, an oxidizer, and 0.1-3.0 wt % of combustion catalyst. M represents a hydrazino radical, ammonium radical, alkali metal, or alkaline earth metal, and the oxidizer is a metal peroxide, inorganic perchlorate, or metal nitrate.
In addition, U.S. Pat. No. 3,741,585 describes a combination of a metal azide and a metal sulfide or iodide; U.S. Pat. No. 3,895,098 describes a combination of an alkali metal azide and a metal oxide; and U.S. Pat. No. 3,931,040 describes a combination of an alkali metal azide, a metal oxide, and a metal carbonate
Furthermore, Japanese Patent Publication No. 13735/1981 describes a formulation composed of a metal azide, an oxidizer, and a compound represented by (Al.sub.2 O.sub.3).sub.m (M O).sub.n (SiO.sub.2).sub.p.qH.sub.2 O (where, M represents Li, Na, K, Sr, Mg, or Ca); and Japanese Patent Publication No. 20920/1983 describes a composition composed of a metal azide, an oxidizer, and silicon dioxide and/or boron oxide or metaphosphate.
The disadvantage of the conventional compositions is that many filters are required to remove metal ions and/or metal oxide formed by combustion, thereby to obtain a pure gas. This leads to large, heavy gas generators.
The present invention was completed to overcome the above-mentioned disadvantages involved in the prior arts.